In general, a patch includes an adhesive layer and a release liner on at least one surface of a backing, the release liner being for protecting the adhesive layer before use of the patch. The release liner is desired to be adequately easy to peel off from the adhesive layer. More specifically, if the release liner is difficult to peel off from the adhesive layer, one has a difficulty in using the patch in the process of attaching the patch to the skin, and, in extreme cases, a problem arises in that the adhesive layer peels off from the backing while the release liner remains adhered to the adhesive layer. On the other hand, the release liner in a state excessively easy to peel off from the adhesive layer may move out of alignment with the adhesive layer during manufacturing or storage of the patch, and cause a problem in that the adhesive layer cannot be protected sufficiently by the release liner.
Thus, there have been used so far patches in which what is termed release treatment is applied to the surfaces of release liners in order to improve the releasability of the release liners. Here, in the release treatment, a release agent such as a silicone-based resin or a fluorine-based resin is applied in the form of a layer to the surface of a release liner, and then is fixed by crosslinking or the like.
Meanwhile, Japanese Unexamined Patent Application Publication No. 2009-274959 (PLT 1) states that, in a patch including an adhesive layer containing a silicone-based adhesive as an adhesive base agent, the adhesive layer is blended with a polar silicone oil, and this silicone treatment on the adhesive layer improves the releasability of a release liner.